This invention relates to implantable articles and methods for manufacturing such articles. More particularly, the invention relates to bone prosthesis and process for manufacturing the same.
There are known to exist many designs for and methods for manufacturing implantable articles, such as bone prostheses. Such bone prostheses include components of artificial joints, such as elbows, hips, knees and shoulders.
A femoral bone is prepared for replacement hip stem prosthesis by expanding the internal cavity of the femoral bone by using a broach or rasp. The broached cavity is filled with bone cement either before or after the insertion of the hip stem prosthesis.
An important consideration in the design and manufacture of virtually any implantable bone prosthesis is that the bone prosthesis has adequate fixation when implanted within the body. 
Early designs of implantable articles have relied upon the use of cements such as polymethylmethacrylate (PMMA) to anchor the implant. The use of such cements can have some advantages, such as providing a fixation that does not develop free play or does not lead to erosion of the joining faces postoperatively.
In the method in which a hip stem prosthesis is inserted after the cement is introduced into the broached cavity, it is important to centralise the stem within the prepared femoral cavity and to maintain the pressure of the cement surrounding the hip stem prosthesis. Centralisation of a hip stem prosthesis and pressurisation of the cement have been linked to long term stem survivability in hip replacement surgery. Loss of pressure of the cement may permit blood to displace some of the cement within the broached cavity.
Known pressurizer devices are either removed prior to stem introduction or a part of the pressurizer is removed or changed to a separate component thereby disturbing the cement and the pressure generation. It is an object of the present invention to maintain the pressure on the cement with little or no disturbance.